It is not uncommon for stacked pieces of furniture or the like to be keyed to each other. In such applications, however, the keys and key ways are sufficiently unattractive that they must be covered or removed when the stacked pieces are used individually. Other stackable devices such as those disclosed in Joyce U.S. Pat. No. 3,581,906 and 3,606,959 obtain alignment by engagement of back members with slots and related devices. The Joyce structures, however, require additional pin bolts or straps to prevent inadvertent horizontal motion between the stacked devices.
Other stackable devices such as those disclosed in Bush U.S. Pat. No. 3,260,396 use upwardly-projecting tabs to extend into upper containers for preventing relative transverse movement. Such structures, however, lack the simplicity and attractiveness that are required for the instant invention's booster chairs which must have their locking structures almost entirely unobservable in order to render them satisfactory for multiple use. Use, that is, as either a piece of furniture in the home or in a restaurant where it is desirable that they be conveniently and attractively stackable.
Additional advantages of the structure of the invention are that the booster chairs are easily cleaned and also provide ventilation for the child that is using the chair. Still further, when the booster chairs of the invention are stacked in a restaurant environment the seats can be used as convenient shelves to temporarily store menus or the like or to have children's favors or utensils temporarily affixed thereto so that they are immediately available to the users at the time of being seated.